Webster’s Revised Unabridged Dictionary · 1913
Arithmetical
Ar′ith·met′ic·al (ăr′ĭth·mĕt′ĭ·kal), a. Of or pertaining to arithmetic; according to the rules or method of arithmetic.
Arithmetical complement of a logarithm. See Logarithm. — Arithmetical mean. See Mean. — Arithmetical progression. See Progression. — Arithmetical proportion. See Proportion.